Synthesis and study properties polymer with semiconductor

مقدم أطروحة جامعية

al-Jabburi, Randah Kamil Husayn

الجامعة

الجامعة التكنولوجية

الكلية

-

القسم الأكاديمي

قسم العلوم التطبيقية

دولة الجامعة

العراق

الدرجة العلمية

دكتوراه

تاريخ الدرجة العلمية

2006

الملخص الإنجليزي

In this work, simple and low cost method is adopted to prepare thick layers of lead iodide (Pbl2) ; solution deposition method provides a chance to deposit large area with appropriate designed thickness, not needing complex techniques or assistance agents.

Layers prepared by this method have the same properties of layers deposited in other methods.

This work studies the influence of doping and annealing conditions (temperature and time) on the properties of lead iodide; three types of dopants were used with three different weights (0.0025, 0.005 and 0.0075gm), namely : AgN03, CdS04 and CaCl2.

While annealing influence is studied in range (75-200 °C) for 1 hour and 2 hours.

The present study focused on the structural, electrical and optical properties of films prepared under different conditions.

The experimental results of XRD showed polycrystalline hexagonal structure with four main peaks which correspond to (001), (101), (003), and (004) at d-6.807, 3.505, 2.304 and 1.713 A respectively.

It is found that the peak intensity changed with doping and annealing, and some shifts of peak positions accompanied the doping and annealing.

The electrical measurements showed the electrical conductivity of Pbl2 was (4.163 x l0~14 S.cm"1) and it increased when the film is illuminated by white light to (1.701 x l0'12 S.cm"1).

The best ratio of photoconductivity to dark conductivity obtained from annealed undoes Pbl2 at 200 °C for 2 hour (68.34).

This ratio sharply decreased by doping, where the dark current is increased with increasing doping weight and with increasing annealing temperature; Ag and Cd dopants cause increment in dark conductivity (

While adding the same amount of Ca caused dramatic Also the activation energies determined for different samples and their values changed within the range (0.0307-1.115 eV).

According to linearity properties, it is found at voltage (> 350 V) and power (> 15xl0"5 W) it is close to the super linear behavior, while the behavior is more or less linear in the voltages (250-300V).

For lower applied voltage (< 200 V) the behavior is sub linear.

The linearity of Pbl2 is enhanced by doping, where the photocurrent is super linear at (> 250 V) and for incident power > 0.3 mM, that is clear in 0.0025gm of Ag, 0.005gm Cd and 0.0075 gm.

Ca doping case.

The optical data were analyzed and interpreted in term of direct electronic transitions.

Transmission spectrum of undoes lead iodide exhibit a sharp increment start around (-520 nm) and it becomes sharper with doping, and shifts occur by doping or by annealing.

It was observed that lead iodide has wide direct band gap (2.36 eV), the energy gap is affected by doping and annealing; it decreased as the doping weight increased and as annealing temperature increased.

التخصصات الرئيسية

الفيزياء

الموضوعات

• الخواص الكهربائية
• أشباه الموصلات
• الإلكترونيات
• تلدين المعادن

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-305981